Following fracture or surgical treatment of the spine, it is often necessary to attach or fix a bone plate to two or more spinal vertebrae via a screw assembly in order to stabilize the spine, to promote fusion, and to expedite mobilization of a patient. One difficult aspect of affixing a bone plate to the vertebrae is the positioning of surgical instruments and implant components within the surgical site. This difficulty is often attributable to the relatively high level of precision required during this surgical procedure.
The need for a relatively high level of precision is due to a number of factors. First, the surgical opening is usually only two or three inches long, which provides a limited field of vision for the surgeon, and limits freedom of movement within the surgical site. Second, the spine is a particularly sensitive and delicate part of the human body that does not lend itself to in-depth probing or exploration. Third, delicate soft tissue proximate the surgical site must be retracted during the surgery without being cut or perforated.
The requisite level of precision, however, is often difficult to achieve in view of the inability to know, in advance, the specific bone plate geometry required to provide optimal stability for the spine. Usually, several bone plates must be temporarily secured to vertebrae and subsequently removed from the surgical site before finding a proper bone plate geometry. But, each insertion and removal of a bone plate increases the likelihood of surgical imprecision.
A number of temporary fixation pins and screws have been developed that allegedly facilitate the temporary fixation of bone plates to two or more vertebrae. These prior art temporary fixation pins and screws, however, suffer from certain drawbacks. For example, a fixation screw is generally sharp enough to penetrate bone. This sharpness can easily damage tissue, however, given the delicate nature of the spine and the soft tissue encountered at the surgical site, coupled with the relatively narrow visual opening into the surgical site.
It would therefore be desirable to provide a device that facilitates the safe and precise temporary fixation of a bone plate to two or more spinal vertebrae.